fix broken tests

1) mtime was not being modified when `--force` was set on command line
This has now been fixed - the force option now overrides Jammit's mtime
niceties

2) newlines for JSTs were improperly described in the tests - the JS
file, including templates and the JST definition, have all literal
newlines stripped, but newlines inside of strings (in the templates
themselves) are not stripped. Since calling jammit on the CLI treats the
whole output as a JS file, the fixture for the `pack_templates` unit
test was not appropriate for the CLI test